Hygrometer.



J. A. THOMPSON..

Patented July 18,1911.

COLUMBIA PLANOuRAPH c0., WASHINGTON, n. c.

UNITED STATES PATENT OFFICE.

JOHN A. THOMPSON, OF ROCHESTER, NEW YORK, ASSIGNOR TO TAYLOR INSTRUMENTCOMPANIES, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

I-IYGROMETER. I

T 0 all whom it may concern:

Be it known that I, JOHN A. THoMPsoN, of Rochester, in the county ofMonroe and State of New York, have invented certain new and usefulImprovements in I-Iygrometers; and I do hereby declare the following tobe a full, clear, and exact description of the same, reference being hadto the accompanying drawings, forming a part of this specification, andto the reference-numerals marked thereon.

The present invention relates to hygrometers of the wet bulb type andithas for an object to make provision whereby greater accuracy issecured in the readings of the instrument.

Another object is to provide a simple and inexpensive connection betweenthe reservoir and the thermometer which enables the reservoir to be madeof glass so that the level of the liquid in the reservoir may beimmediately ascertained.

Still another object is to provide an improved means for obtainingreadings at a substantially constant temperature without any materialcalculations.

To these and other ends the invention consists in certain improvementsand combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims at the endof the specification.

In the drawings: Figure 1 is a front elevation of the hygrometer, andFig. 2 is a section on line aa, Fig. 1.

In the present embodiment the thermometer 1 is supported on a plate 2which has a scale 3 extending along the stem. This scale has divisionsindicating degrees of saturation of the air at a certain dry bulbtemperature, say 103 Fahr. thus adapting the device for use inincubators or other places where the temperature is substantiallyconstant. In order that other readings may be obtained from the scale atother and proximate dry bulb temperatures with but slight calculationsinstructions 4: are arranged on the plate 2.

Water is fed to the thermometer from a reservior 5 by means of acapillary member or wick 6 which may at one end surround the thermometerbulb. The reservoir is preferably transparent, being made of glass, inorder that the level of the water may be ascertained. The wick in thisinstance con- Specification of Letters Patent.

Application filed October 2'7, 1909.

Patented July 18, 1911.

Serial No. 524,907.

nects with the reservoir at a point below the uppermost water level sothat the immersed portion will be constant. This is very important asthe wick always receives the same amount of water and the water supplydoes not decrease with the lowering of the water level. It is preferredto construct the reservoir with a small throat 7 at one end turnedupwardly slightly, the water being held from discharge through thethroat by making the reservoir air tight above the discharge. Feet 8 arearranged nearer to the throat end of the reservoir than to the oppositeend so that the reservoir will lie at a slight inclination.

The thermometer is preferably supported on the reservoir and as thelatter is made of glass a connecting means should be provided which willprevent injury to the reservoir. In this instance the plate 2 carries aclamp in the form of two spring arms curved to conform to the reservoirand adapted to embrace and interlock with the latter by cooperating withopposite sides of the same. This clasp performs the function of a saddleand permits the parts to be separated for renewal or for shipment.

In operation the hygrometer is placed within a chamber having asubstantially constant temperature, the reservoir having been previouslyfilled with water and the parts connected as shown in Fig; 1. The waterwill be carried by capillary action to the thermometer bulb andevaporate, the amount of evaporation being dependent on the moisture inthe chamber. The evaporation on the bulb affects the latter and causesthe thermometer to indicate the humidity, say at 103 Fahr. The humidityat other proximate temperatures may be obtained by following theinstructions on the plate 2.

A hygrometer constructed in accordance with this invention gives moreaccurate readings as the immersed portion of the capillary member isconstant. The level of the liquid in the reservoir may be ascertainedwithout handling the device and the reservoir will last longer as it isnot subject to leakage. If it becomes broken it may be easily replacedby another.

I claim as my invention:

1. In a hygrometer, the combination with a reservoir of transparentmaterial, of a thermometer arranged exteriorly of the reservoir, aspring clamping member supreservoir on opposite sides to supportthe 10bulb of the latter on the exterior of the reservior, and :1 capliiarymember leading trom the reservoir to the bulb of the thermometel'.

JOHN A. THOMPSON. Witnesses H. H. SIMMs,

tossisLL B. GRIFFITH.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. C.

